The field of the present invention relates to breathing circuits or more particularly to a flexible tubular device to be connected to a breathing apparatus or anaesthetic system on one end with the other end applied to nasal or oral regions of a patient. The present invention is particularly applicable for infants and premature babies.
There are existing flexible tube devices which include a coaxial arrangement with a first tubular member on the outside and a second smaller tubular member running coaxially inside the first tubular member. Another existing device is the parallel line design illustrated in FIG. 1b having corrugated inspiratory tubular member 240 separate from corrugated expiratory tubular member 230. A device of the coaxial design is disclosed in Bain U.S. Pat. No. 3,856,051. The Bain device is illustrated in FIG. 1a. Referring to FIG. 1a, the Bain device 100 is comprised of a corrugated outer tubular member 110 and an inner tubular member 120 running inside the corrugated member 110. Typically the inner tubular member 120 is the inspiratory channel and the outer corrugated tubular member 110 (or more specifically the volume between the inner and outer tubular members) is the expiratory channel.
This corrugated tubular device has several deficiencies. In particular, the corrugated tubular member 110 must be flexible enough to allow convenient movement and adjustment of the tube 100 while simultaneously providing sufficient stiffness and structural strength to withstand damage from use, avoid collapse, and provide structure for attachment of additional tubings which may be required for a particular application. It is also desirable that both the expiratory and inspiratory channels exhibit low air flow resistance.